1. Field of the Invention
The invention relates to the use of nonionic cellulose ethers selected from the group consisting of hydroxyethyl cellulose, hydroxyethyl-methyl cellulose, hydroxypropyl-methyl cellulose and hydroxypropyl cellulose having a Brookfield viscosity in a 2% aqueous solution at 20.degree. C. of at least 3000 mPa.s and preferably at least 5000 mPa.s, as additives for joint-sealing materials and coating materials which are based on aqueous dispersions of polyacrylates or acrylate copolymers to improve the brushability and the smoothing behavior of not yet hardened surfaces of these materials.
2. Discussion of Related Art
It is known from Ullmann, Enzyklopaedie der technischen Chemie, 4th. Edition, pp. 208-209 that nonionic cellulose ether derivatives such as hydroxyethyl cellulose (HEC), hydroxyethyl-methyl cellulose (HEMC) and hydroxypropyl-methyl cellulose (HPMC) may be added to synthetic resin plasters to improve their water-retention capacity, workable period, wet-adhesion and thickening and setting behavior. German patent 36 19 142 discloses the further use of water-soluble cellulose derivatives as auxiliary agents in the mechanical smoothing of unhardened surfaces of pasty materials, particularly joint-sealing materials, e.g., those based on polyacrylates.
The generally known formulations of joint-sealing materials and coating materials, after application, are normally smoothened out with smoothing water or water/wetting agent mixtures, e.g. as in German patent 36 19 142. The use of smoothing agents makes it possible to form both technically and optically faultless connections with bordering structures and to even out imperfections in the surfaces of these materials. The accumulation of the wetting agents contained in the smoothing agent causes reduction of the slip-resistance on the surface of the jointing agent and makes slippage itself a possibility. Under certain preconditions the accumulation of wetting agents results in the emulsification of formulation constituents on the surface of the materials. Because this alters the composition of the material at its surface, the technical properties of the jointing agent can be impaired. The depletion of constituents of the material at its surface can equally be disadvantageous.